Vehicle operating and speed regulating device

ABSTRACT

A vehicle operating and speed-regulating system for a motor vehicle having a transmission and an engine accelerated and decelerated under control of gas and brake pedals, wherein vehicle speed is maintained at a constant value preset by actuation of one of the pedals just before both pedals are released. The constant speed maintaining action of the system is effected by regulating both shifting of the transmission and optimized operation of the engine pursuant to calculations made to attain driving conditions in accordance with diagrammed characteristics of the engine.

BACKGROUND OF THE INVENTION

This invention relates to a vehicle operating and speed regulatingdevice.

BRIEF DESCRIPTION OF THE PRIOR ART

Operating a vehicle with an automatic transmission in the drive path bymeans of a gear shift lever and a gas pedal, where the drive ratio ofthe engine is regulated by the driver by means of the known gas pedalaccording to the desired driving speed and the running resistances--forexample, ascending gradients, descending gradients and air resistancedepending upon driving speed--is known. In that situation, thetransmission is shifted according to relatively roughly differentiatedload-controlled shift points in accordance with the engine'scharacteristic diagram as shown in ATZ 85 (1983) 6 from page 401.

Influencing the engine through a speed regulator so that the vehicletravels at a nearly constant speed without actuation of the gas pedal,with the transmission also being involved in the adjustment to thepreset speed through another electronic device, is also known.

And finally, along with the actuation of the speed regulator by a firstactivating key after the interruption of this device by activation ofthe brake pedal, attaining the previously set vehicle speed again by asecond activating key without activating the gas pedal is known fromDE-OS 35 06 363.

When that is the situation, the previous driving speed is desired andattained, in a preprogrammed acceleration, when the engine power and therunning resistances present--ascending gradients, for example--permitit.

Such devices improve the operation of a motor vehicle and can lead to aconsumption-oriented way of driving in constant travel and duringacceleration. But the overall effect is relatively slight since thisdevice is seldom used because of the additional control that isrequired. Manipulation is also necessary and complicated, so that use isalmost exclusively in very quiet traffic situations.

Therefore, it is the object of the invention to further develop avehicle operating and speed regulating device so that an electroniccontrolling and regulating device influences engine and transmissionoperation more advantageously and further relieves the driver in thetask of operating the vehicle.

SUMMARY OF THE INVENTION

The reduction of vehicle operation to an acceleration pedal anddeceleration pedal, both of which work on an electronic controlling andregulating device, not only simplifies operation but also makes theapplication of an optimal adjustment of engine, transmission and vehicleperformance possible under all driving conditions. In that situation,the electronic controlling and regulating device comprises a commondevice for influencing the engine, keeping speed constant, controllingtransmission and clutch operation and interlinked individual controlmechanisms for the main function, as is known from DE-OS 35 06 363. Bythe combination of the acceleration and deceleration pedals with theelectronic controlling and regulating device and as a result ofexpansion of the influence of the engine and transmission in combinationwith the simple operation, the desired driving conditions can be linkedmuch more optimally with the engine and transmission characteristics.

No driver is able to actuate a gas pedal so that the engine is alwaysoperated in the optimum of the characteristic diagram. In knownautomatic transmissions, the shift points or shift cycles are preset forthe transmission, depending upon the gas pedal's position, by anelectronic control mechanism, so that a high pendulum dynamic is alsofollowed by a high shift point change. With the present invention, thedriver only continues to choose the driving condition and not the engineload and the transmission condition. Instead, the electronic controllingand regulating device registers the desired driving conditions that arefed in by the driver through the acceleration and deceleration pedalsand selects engine load and transmission multiplication according to apreset strategy, for example fuel consumption, whereby considerablygreater shares of the driving are obtained in the optimal operatingrange of the engine. Changing the running resistances at a constantspeed is also managed considerably more sensitively by a sequence ofautomatic operations in the electronic controlling and regulating devicethan by a driver. This system also offers a higher degree of safetybecause the driver can reduce his reaction time before preventivebraking, even at constant speed.

All of the advantages of the system can only be fully used with anautomatically shifting transmission. But simple advantages also emergewith a semiautomatic transmission, or even with a transmission thatfundamentally is shifted by hand. The conclusions of the electroniccontrolling and regulating device are passed on to the driver opticallyor acoustically in the form of recommendations such as high or reversegear requests. However, the fully-automatic layout is faster and simplerfor the driver because the desired driving condition is continuallycompared with the actual condition in the drive path. The most favorableengine speed in combination with the most favorable gear can be selectedimmediately if the gradients are not in accordance with the change inpower and a function of the programmed driving strategy, and is given tothe actuation devices in the engine and transmission to be put intoexecution. This process makes it possible to continuously seek theoptimum program of work between engine and transmission which cannot beachieved when the drive does the gear shifting.

The electronic controlling and regulating device is easily adaptable tovarious requirements in a relatively simple manner with suitableprogramming without any change in the handling by the driver. Anotherfavorable adaptation can be achieved by the freely programmableacceleration requirement in combination with the actuation of theacceleration pedal. The functions triggered by the actuation of thedeceleration pedal result in further simplifications of operationbecause several logically connected functions are put into execution byonly one operating device. Through timing elements in the electroniccontrolling and regulating device, especially in connection with theactuation of the deceleration pedal, all desired functions can beobtained as a function of the operating dynamic. Moreover, free-wheelingcan be triggered in addition to or in combination with the actuation ofthe acceleration pedal because, for example, the latter is desired indownhill travel in combination with a desired vehicle speed, where theconstant speed can be of subordinate importance in such a drivingsituation.

FURTHER DESCRIPTION OF THE FIGURES

Further details of the invention will be explained in the light of theaccompanying drawing, in which:

FIG. 1 shows a block connection diagram of the vehicle operating andspeed regulating device;

FIG. 2 shows a control curve of the acceleration as a function of theactuation angle on the acceleration pedal;

FIG. 3 shows a running resistance representation in several runningresistance curves;

FIG. 4 shows a rough process in a vehicle operating and speed regulatingdevice; and

FIG. 5 shows a performance charactertistic diagram.

DETAILED DESCRIPTION

In the block connection diagram of the vehicle operating and speedregulating device according to FIG. 1, an engine 1, a clutch 2 and anautomatic transmission 3 are provided where the automatic transmissionand the clutch can be designed as a planetary gear system with abridgeable torque transformer as a clutch, as is known, or as anautomated gear reducer transmission with a separately-disposed automateddry or wet clutch, for example. The electric controlling and regulatingdevice 4 is connected with the engine 1, with the clutch 2, and with thetransmission 3 by control cables 41, 42, 43 to influence it. The enginespeed, the transmission-input revolutions per minute and theclutch-output revolutions per minute and the transmission output speed,as well as the transmission position are supplied to the electroniccontrolling and regulating device 4 through suitable sensors or servounits 9 through leads 11, 21, 31 and 32. Furthermore, the electroniccontrolling and regulating device 4 is supplied with hand brake 71 andfoot brake 72 activation information and the output speed 73--possiblefrom all drive wheels--from the vehicle 7. The vehicle's service brake,which may comprise both a generally known parking brake and also ahydrodynamic brake, is directly influenceable as well as influenceablethrough the controlling and regulating device, and consequently throughthe lead 44. For operation, the acceleration pedal 5 is connectedthrough the control cable 51 and the deceleration pedal 6 through thecontrol cables 61, 62 and the gear selection device 8 through the cable81, with the electronic controlling and the regulating device 4.

FIG. 2 shows a control curve 52 that represents the acceleration a as afunction of the actuation angle or the actuation path of theacceleration pedal 5.

In FIG. 3, the running resistance power P over the vehicle speed V isshown, with the curve LR representing the air and rolling resistance onflat terrain. The other, more weakly drawn curves LR1 to LR3 involvevarious climbing resistances and LR4 to LR6 show the displacement thatresults from a downhill run. Computational intervals that arise in anaccelerated run on flat terrain, for example, are indicated with A.

FIG. 4 shows the greatly simplified functioning in the electroniccontrolling and regulating device 4. With the actuation of theacceleration pedal 5 and the deceleration pedal 6, the driver feeds thedesired driving condition into the electronic controlling and regulatingdevice 4. The power difference 45 in the time interval is calculatedfrom the actual condition analysis that is made up of the revolutionsper minute, cables 11, 21, 31 of the engine 1, clutch 2 and thetransmission 3, as well as the engine load 12 and the gear-shiftposition 32 from the transmission 3 and the flow of signals from thevehicle 7 including the foot brake 72, hand brake 71, and output speedsignals and the desired driving condition. Taking the pedal and vehicledynamics into consideration, the gradient for the power change 46 isthen extrapolated. The engine load and engine speed change 47 resultfrom another calculation while taking a consumption optimum and thevehicle dynamic (frequency of shifting) into consideration.

In another calculation, the new transmission position 48 is calculatedfrom the new engine speed. Then the signal output 49 for the influencingof the engine 41, influencing of the clutch 42 and influencing of thetransmission 43 is produced.

In the engine characteristic diagram according to FIG. 5,

T=torque (NM)

nM=engine speed (1/min)

be=specific consumption (gKWh)

P=line-constant running resistance power (KW)

B=running resistance line of a first transmission multiplication

C=running resistance line of a second transmission multiplication

P₁ =running resistance power before gear shifting

P₂ =running resistance power after gear shifting

The shifting process in shiftings of conventional automatic transmissionis marked with the line P₁ to P₂ '. As shown, the power in point P₂ 'after shifting is less than before. Thus the driver must compensate forthe power difference with the gas pedal. At the same time, automatictransmissions shifted in that way tend toward gear-shifting oscillationwith unfavorable running resistances.

The shifting process with constant power is represented by the curvefrom P₁ to P₂. Since the electronic controlling and regulating mechanismknows the gear multiplication that is available, it selects themultiplication with which the most favorable consumption can be achievedat constant power, for example. Thus, gear shifting with the gear leap Xis not carried out at constant torque, but the automatic transmissiontakes over the readjustment (range of adjustment Y) immediately afterthe shifting of gears. Thus, the correct engine load is fed inimmediately after the engine engagement resulting from the gearshifting. As a result, the same power is available to the driver afterthe gear shifting. Thus he only needs to intervene when he would like tochange his driving condition by further acceleration or deceleration.

The vehicle operating and speed-regulating device functions as follows:

The acceleration pedal 5 is actuated (i.e. depressed) by the driver aslong as the driver would like to accelerate. The magnitude of theacceleration can be varied in each case according to the pedal angle. Apossible example is derivable from the control curve 52 of FIG. 2.

Pedal angle is proportional to the acceleration,

small angle means small acceleration,

large angle means big acceleration.

This signal proportional to the actuation angle or path is conveyed tothe electronic controlling and regulating device 4 through the controllead 51. If the desired speed is achieved, the driver eases off on theacceleration pedal. By that means, the engine load and, in connectionwith an automatic transmission 3, the multiplication, are accomodated tothe changing running resistances by a vehicle speed regulating device,known in the art, that can be integrated in the electronic controllingand regulating device, but also can be provided separately. Theadjustment of engine and transmission is selected according to a drivingstrategy--consumption-oriented, for example.

If the tempostat action is to be discontinued, the deceleration or brakepedal 6 is activated by the driver. In that connection, the pedal anglesmentioned in the following are differentiated.

1. Very small angle--the tempostat action is discontinued by a signal oncontrol lead 61 and at the same time the clutch 2 can be opened by theelectronic controlling and regulating device through the control leads42 or 43 or the transmission can also be put in neutral without anadjustment of the gear shift lever 8 being required. By that means, afree-wheeling effect is obtained that results in a reduction, or in thecase of downhill an increase, of speed depending upon the drivingprofile or the running resistance in each case.

2. Small angle--the tempostat action is already discontinued byactivation with a very small angle. The clutch is or has been closed andthe transmission is or has been shifted into a gear corresponding to thedriving speed so that an engine-braking action results. By that means,relatively high shift points for a reverse-gear shift can still becomeeffective, so that the engine-braking action is reinforced.

3. Bigger angle--when a specified small actuation angle is exceeded, theservice brake is activated. This can take place directly, but alsothrough the electronic controlling and regulating device. When thevehicle is equipped with a device that prevents an overloading of theservice brake, the deceleration pedal acts on the service brake throughthe electronic controlling and regulating device. Furthermore,combination with a wear-free hydrodynamic brake, or similar devices suchas a brake energy storage device, for example, is possible. At leastafter exceeding the small actuation angle, the deceleration pedalfunctions in a manner similar to the acceleration pedal.

Deceleration pedal angle is proportional to the deceleration, wheresmall angle yields smaller deceleration and a large angle yields biggerdeceleration.

The deceleration pedal is actuated (i.e., depressed) until a desireddecelerated speed is reached. After that, the speed is maintained again.

Thus, the automatic transmission calculates, according to the angle ofthe deceleration pedal 6, the brake energy required, beginning with onlythe running resistance through the engine brake action to the servicebrake. The function mentioned above in connection with the activation ofthe deceleration pedal could also be the same in connection with theacceleration pedal 5, in which case a brief tapping of the accelerationpedal could bring about the free-wheeling action, for example.

In the electronic controlling and regulating device 4, the accelerationselected by the driver is calculated constantly. When that is done, therequired engine power during the acceleration phase is:

    P=Pw+Pa

P=engine power

Pw=running resistance power

Pa=acceleration power

As power modification, the following results:

P₂ -P₁ =Pw2-Pw1+Pa2-Pa1

As a result of very small time intervals,

    Pw2=Pw1

can be assumed.

From

ti Pa=m·km·a·V

M=mass

km=correction factor for rotation masses

a=acceleration

V=speed

the following results:

    P.sub.2 P.sub.1 =m·km (a2·V2-a1·V1)

Depending upon vehicle type and accuracy required, m·km can bestipulated as vehicle-constant or calculated from the vehicle dynamicwhen bringing to speed.

The acceleration preset by the driver through the angle of theacceleration pedal is a theoretical preset quantity with no influence ofrunning resistances taken into consideration. The acceleration that isset is a partial value of the maximum acceleration for the runningresistance at that time corresponding to the pedal angle.

Furthermore, the possibility of carrying out a continuous adjustment ofdesired acceleration to the measured actual acceleration by a comparisonexists.

Thus, the power required for the acceleration selected by the driver iscalculated continuously. The optimal values for engine filling ratio andmultiplication in the transmission can be determined by the electronicapparatus by simple selection criteria.

In constant travel and changing running resistances, the required powerdifference is also calculated and the optimum for engine load andtransmission multiplication calculated according to appropriateselection criteria.

I claim:
 1. Apparatus for controlling the acceleration and deceleration of a motor vehicle having an engine, an automatic transmission, a clutch coupling the engine with the transmission, and gas and brake pedals in order to optimize engine performance and to maintain a given vehicle speed established by operation of the pedals, comprising(a) means for continuously sensing the position of the brake pedal; (b) means for continuously sensing the position of the gas pedal; (c) means for continuously sensing the speed of the vehicle and the operating conditions of the engine, clutch, and transmission, respectively; (d) first means for continuously calculating a power difference, a gradient for power change and the engine load and speed change in accordance with the sensed positions of the brake and gas pedals and with the sensed vehicle speed and operating conditions of the engine, clutch and transmission; (e) second means for continuously calculating a transmission position in accordance with a new engine speed resulting from said calculation of engine speed; and (f) means for producing control signals delivered to the engine, clutch and transmission to control the operation thereof for acceleration and deceleration of the vehicle, whereby a desired vehicle speed is maintained.
 2. Apparatus as defined in claim 1, wherein said second calculating means are further operated in accordance with the operating parameters of the engine.
 3. Apparatus as defined in claim 2, wherein said engine operating parameters include fuel consumption, exhaust gas value, and load, whereby said control means may be used to automatically control vehicle performance while optimizing engine efficiency.
 4. A method for controlling the acceleration and deceleration of a motor vehicle having an engine, an automatic transmission, clutch coupling the engine with the transmission, and gas and brake pedals in order to optimize engine performance and to maintain a given vehicle speed established by operation of the pedals, comprising the steps of(a) continuously sensing the position of the brake pedal; (b) continuously sensing the position of the gas pedal; (c) continuously sensing the speed of the vehicle and the operating conditions of the engine, clutch and transmission, respectively; (d) continuously calculating a power difference, a gradient for power change and the engine load and speed change in accordance with the sensed positions of the brake and gas pedals and with the sensed vehicle speed and operating conditions of the engine, clutch and transmission; (e) continuously calculating a transmission position in accordance with a new engine speed resulting from said calculation of engine speed; and (f) producing control signals delivered to the engine, clutch, and transmission to control the operation thereof for acceleration and deceleration of the vehicle, whereby a desired vehicle speed is maintained.
 5. A method as defined in claim 4, wherein the difference in engine power output is calculated according to the following formula:

    P.sub.2 -P.sub.1 =m·km(a.sub.2 ·V.sub.2 -a.sub.1 ·V.sub.1)

wherein m=mass km=correction factor for rotation mass a=acceleration V=speed P=engine power
 6. A method as defined in claim 5, wherein the calculation of required change in engine power is performed in accordance with the operating parameters of the engine.
 7. A method as defined in claim 6, wherein said engine operating parameters include fuel consumption, exhaust gas value, and load, whereby vehicle performance is automatically controlled while optimizing engine efficiency. 